Bag bodies each equipped with a plastic zipper having a slider are widely employed for a variety of articles in the fields of foods, pharmaceuticals, electronic part items and the like. There have hitherto been proposed various items relating to the structure of this kind of plastic zipper and a slider for opening and closing the same {for instance, Japanese Patent Application Laid-Open No. 214920/1996 (Heisei 8)}. In general, the structure of a plastic zipper is constituted as illustrated on FIG. 16 through FIG. 20.
That is to say, FIG. 16 is a perspective cross sectional view showing the principal portions of a conventional bag body equipped with a slider. FIG. 17, FIG. 18, FIG. 19 and FIG. 20 are each a cross sectional view taken along line E-E′ of FIG. 16, a cross sectional view taken along line F-F′ thereof, a cross sectional view taken along line G-G′ thereof and a cross sectional view taken along line H-H′ thereof.
In the FIG. 16 through FIG. 20, the slider S which is usually comprised of an outside guide 6-1 that is built in a slider main body Sh and an inside guide 6-2 that is inserted between the male hook and the female hook of the plastic zipper in such a structure to disengage the male/female hooks, while the outside guide 6-1 causes the male/female hooks to engage and at the same time, prevent the slider falling off from the zipper. That is to say, the outside guide 6-1 slidably nippes both sides of the plastic zipper so as to engage the male/female hooks, and the outside guide 6-1 also nippes the lower portion of the zipper, namely the anti-falling-off portion 6-1-1 to prevent the slider falling off from the zipper.
In order to attach the slider to a bag body equipped with the plastic zipper in an automatic and mass-producible manner, it is necessary to attach the slider simultaneously with bag manufacture in the case of manufacturing bags with a bag manufacturing machine. Since the manufacturing rate of a bag manufacturing machine is usually about 60 bags per minute, a slider attaching rate is required to be comparable thereto or more than the same.
However, since simultaneous attachment of the inside guide at an opening portion of the zipper and the outside guide at a closing portion of the zipper necessitates a considerably troublesome steps, it is difficult to simultaneously satisfy the above-mentioned requirements. In particular in the case of thin zipper portion with small slider, the slider attaching rate is markedly decreased to an uneconomical level.
In addition, the case where it is possible to use the above-mentioned slider having the anti-falling-off portion 6-1-1 in such form that a portion of the outside guide slidably nippes the lower portion of the zipper has been limited to a case where the size of the zipper is so large as to be capable of preventing the slider from falling off, and also to such a case where the film on which the hooks of the zipper are formed has favorable sliding properties and strength.
That is to say, the slider as mentioned above suffers from a serious disadvantage that it is unusable in the case of a small zipper portion and a film on which the zipper portion is formed and which has a small thickness or poor sliding properties, because of damage to the film or falling-off of the slider.
Moreover, the existence of the anti-falling-off portion causes further intricateness and difficulty to attaching procedure of the slider as well as remarkable decrease in slider attaching rate.
There is also known a slider which is used for a conventional plastic zipper and to which is applied anti-falling-off structure for sliders.
Specifically, FIG. 21 is a perspective view showing a conventional zipper. FIG. 22 and FIG. 23 are each a cross sectional view taken along line I-I′ of FIG. 21 and a cross sectional view taken along line J-J′ thereof. FIG. 24 and FIG. 25 are each a cross sectional view taken along line K-K′ of FIG. 22 and a cross sectional view taken along line L-L′ of FIG. 23. In this case, the lower portion of the slider extends to the engaged portion of the zipper, thereby preventing falling-off thereof.
FIG. 26 and FIG. 27 each show an example of a slider for a conventional plastic zipper equipped with an anti-falling-off structure for the slider and are each a cross sectional view taken along line F-F′ of FIG. 16 (similar to FIG. 18) and a cross sectional view taken along line H-H′ of FIG. 16 (similar to FIG. 20). As can be seen from the figures, the tip portion 6-2-1 of the inside guide 6-2 is inserted beneath the zipper engaging portion, thereby preventing falling-off of the slider.
With such a structure, the slider falling-off can be prevented even in the case of a small-sized zipper. Nevertheless it is remarkably difficult to simultaneously carry out two contradictory procedures wherein for the sake of attaching the slider to the zipper, on the one hand the zipper needs to be opened to insert the inside guide, and on the other hand the tip portion of the inside guide must be inserted into the inside of the closed zipper. Hence taking into consideration the slider attaching rate, the industrial implementation thereof is extremely difficult.
The object of the present invention is to provide a slider for a plastic zipper, a bag body equipped with the aforesaid slider and a process for producing the bag body, wherein the slider can easily be attached to the plastic zipper at a rate higher than a bag manufacturing rate, and further is free from a fear of falling off even if the plastic zipper is slender and is formed of a film having a thin material and low strength.